The purpose of these workshops is to develop recommendations for measuring lung volumes in humans (infants, children and adults) by body plethysmography, gas dilution and washout, and radiographic and CT techniques. The limits of each of these technologies will be clearly defined. The workshops will also address recommendations regarding predictive normal values, and interim conclusions with respect to the clinical usefulness of lung volume measurements using the various techniques. Information needed to expand the effectiveness of these measurements in clinical and research settings in the future will be included in the document. The effect the recommended techniques will have on plethysmographic measurements of airway resistance and conductance will be briefly reviewed. This project will be accomplished in two conferences that will bring together expert participants from the United States, Canada and Europe. Presentations of the document for review and comment at one United States and one European meeting will also be included. This will provide broad based input from members of both Societies, a process that we have found useful on previous documents. Comments and suggestions from the manufacturers of the equipment involved will be solicited in a formal manner and taken into consideration in the preparation of the recommendations. This is being done to confirm the feasibility of the recommendations. The document created is intended to become and official Statement of the American Thoracic Society, and have official status conferred by the European Respiratory Society and the European Coal and Steel Community.